I didn’t start running till I was nearly 40, but luckliy had never smoked. It took 12 hard months to achieve this, I started with treadmills and got further and faster. Once I could run a 5min km on the machine for 5km then I moved outside more. Slowly increasing to 6 then 8 then 10 km but at the same 5min pace. My goal was actully to do a classic run in Adelaide called the City to Bay which is 12 km in under an hour but this 10km goal was an important one which really helped.